Coupling RuO nanofibers with ionic crystal significantly enhances the water electrolysis performance.

Ruthenium (Ru) has emerged as a highly promising and cost-effective alternative to Ir- and Pt-based electrocatalysts for water electrolysis, making the development of efficient and stable Ru-based bifunctional catalysts a critical research objective. Herein, an AgCl/RuO heterojunction is prepared via a facile electrospinning-calcination strategy. The AgCl undergoes a reduction to form metallic Ag under hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) processes, which can be integrated with RuO active sites to facilitate HO dissociation and enhance the electron transfer while simultaneously suppressing RuO over-oxidation. Therefore, the optimized AgCl/RuO-300 NFs demonstrate exceptional HER performance, achieving an overpotential of only 105 mV at 1000 mA cm in 1 M KOH, along with remarkable stability, maintaining continuous operation for 270 h at this high current density. Furthermore, this catalyst also displays favorable alkaline OER performance, requiring overpotentials of just 214 and 275 mV to reach 10 and 100 mA cm, respectively. Crucially, an electrolyzer assembled with this bifunctional catalyst achieves 10 mA cm at a low cell voltage of 1.49 V, outperforming commercial Pt/C||RuO system and most recently reported electrolyzers. Additionally, the AgCl/RuO-300 NFs show significant potential for seawater electrolysis, demonstrating exceptional corrosion resistance and robust stability. This work offers a novel strategy for designing highly active and durable Ru-based electrocatalysts for both alkaline freshwater and seawater electrolysis.